AutoCodes – Mitsubishi – P0155 Mitsubishi

P0155 Mitsubishi Code - HO2S 21 Heater Performance

Quick Answer

Oxygen Sensors (O2S) or Heated Oxygen Sensors (HO2S) need to reach a minimum operating temperature of 750 degrees F to produce an accurate voltage signal. Common causes include Faulty Heated Oxygen Sensor (H2OS) Bank 2 Sensor 1, Heated Oxygen Sensor (H2OS) Bank 2 Sensor 1 circuit fuse, Heated Oxygen Sensor (H2OS) Bank 2 Sensor 1 harness is open shorted to ground. Severity is Moderate - service should be scheduled soon. The vehicle may still be drivable for short trips if it runs normally, but avoid hard driving and repair it soon.

What it means: P0155 Mitsubishi indicates HO2S 21 Heater Performance.
Common causes: Common causes include Faulty Heated Oxygen Sensor (H2OS) Bank 2 Sensor 1, Heated Oxygen Sensor (H2OS) Bank 2 Sensor 1 circuit fuse, Heated Oxygen Sensor (H2OS) Bank 2 Sensor 1 harness is open shorted to ground.
Severity: Moderate - service should be scheduled soon.
Can I drive?: The vehicle may still be drivable for short trips if it runs normally, but avoid hard driving and repair it soon.

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Code Popularity 20,012

How popular is this code, among other codes? Low

Repair Importance Level

Moderate (Service soon) (2 / 3)

Repair Difficulty Level

Intermediate (2 / 3)

What is this?

Table of contents Created and updated by William Orellana on Mar 23, 2024

Description
Step-by-Step Diagnostic Guide
Possible Causes
How To Fix
Tech Notes
Cost to Diagnose
FAQs
Comments
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Code P0155 Mitsubishi Description

Oxygen Sensors (O2S) or Heated Oxygen Sensors (HO2S) need to reach a minimum operating temperature of 750 degrees F to produce an accurate voltage signal. The faster the heated oxygen sensor reaches that temperature the faster the sensor will start sending an accurate signal to the Engine Control Module (ECM). In order to achieve the require temperature, a heater element is included inside the heated oxygen sensor. The ECM controls the heated oxygen sensor heater element based on signals from the engine coolant temperature and engine load. The ECM controls the heater element circuit by allowing current flow to ground. The ECM monitors the voltage signal received through the heater element circuit and determines the state of the circuit by comparing the voltage detected with the factory specifications.

OBDII Code P0155 Mitsubishi - HO2S 21 Heater Performance - AutoCodes.com — P0155 Mitsubishi Code - HO2S 21 Heater Performance

What does this mean?

What are the Possible Causes of the DTC P0155 Mitsubishi?

Faulty Heated Oxygen Sensor (H2OS) Bank 2 Sensor 1
Heated Oxygen Sensor (H2OS) Bank 2 Sensor 1 circuit fuse
Heated Oxygen Sensor (H2OS) Bank 2 Sensor 1 harness is open shorted to ground
Heated Oxygen Sensor (H2OS) Bank 2 Sensor 1 circuit poor electrical connection
Faulty Engine Control Module (ECM)

How to Fix the DTC P0155 Mitsubishi?

Review the 'Possible Causes' above and visually examine the corresponding wiring harness and connectors. Check for damaged components and inspect connector pins for signs of being broken, bent, pushed out, or corroded.

What does this mean?

Code Tech Notes

The code means that there is a problem with the heater element circuit of the heated oxygen sensor. The Engine Control Module (ECM) monitors how long it take the sensor to warm up and start sending an adequate signal. The code means the the sensor is taking too long to warm up. Replacing the Front Heated Oxygen Sensor (H2OS) Bank 2 usually takes care of the problem.

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P0155 Mitsubishi code, it typically requires 1.0 hour of labor. Rates vary by location, vehicle, and shop. Many shops charge between $80–$150 per hour; dealerships and metro areas may be higher, independents may be lower.

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About the author: William Orellana is a Master Mechanic and Mechanical Engineer with over 30 years of experience diagnosing and repairing vehicles. Learn more about his background.

Frequently Asked Questions about P0155 Mitsubishi Code

What does the OBDII code P0155 mean for a Mitsubishi vehicle?

1. P0155 indicates an issue with the heater circuit of the oxygen sensor (HO2S) located on Bank 2, Sensor 1, meaning it is not heating up properly for accurate readings. 2.

What are the common symptoms of code P0155?

Symptoms may include an illuminated check engine light, decreased fuel efficiency, rough idling, poor engine performance, or increased exhaust emissions. 3.

What causes the P0155 code to appear on a Mitsubishi?

Common causes include a faulty Bank 2, Sensor 1 oxygen sensor, a blown fuse for the heater circuit, damaged wiring or connectors, or an issue with the engine control module (ECM). 4.

Can I drive my Mitsubishi with the P0155 code active?

Driving with P0155 may not cause immediate damage, but prolonged issues can lead to poor performance, increased emissions, and potential damage to the catalytic converter. 5.

How do I diagnose the P0155 code in my Mitsubishi?

Start by checking the oxygen sensor's heater circuit wiring and connectors for damage, test the sensor's resistance, and inspect the fuse for the heater circuit. 6.

How do I fix the P0155 code on a Mitsubishi?

Repairs may involve replacing the faulty oxygen sensor, repairing or replacing damaged wiring, replacing a blown fuse, or reprogramming the ECM if necessary. 7.

How much does it cost to fix the P0155 code?

The cost ranges from $150 to $300 for parts and labor to replace the oxygen sensor, but wiring or ECM repairs may vary based on the extent of the issue. 8.

Can a dirty oxygen sensor cause the P0155 code?

A dirty sensor is unlikely to cause P0155, as this code specifically relates to the heater circuit performance rather than sensor contamination. 9.

Is a special tool required to diagnose or fix the P0155 code?

Yes, a scan tool or OBDII code reader is needed to diagnose and clear the code, and a multimeter may be required to test the sensor and wiring. 10.

What happens if the P0155 code is ignored?

Ignoring the P0155 code can lead to decreased fuel efficiency, higher emissions, potential damage to the catalytic converter, and failed emissions tests.